Conical furnace



Dec. 20, 1960 J. s. WALLIS ET AL CONICAL FURNACE 2 Sheets-Sheet- 1 Filed Jan. 28, 1959 INVENTORS JOHN S l V/JZL/S JOHN W 7f/fi0C/(MOE70N Dec. 20, 1960 J. s. WALLIS ETAL 2,965,080

CONICAL FURNACE 2 Sheets-Sheet 2 Filed Jan. 28, 1959 INVENTORS JOH s. WALL/.5 Y J% T/ /KOMMMMA/ solidated Industries, Inc., 'San Francisco, Calif., a corporation of Delaware Filed an. 28, 1959, Set. No. 789,584 Claims. Cl. 122-356 This invention relates to upright heaters which are usually employed inlarge sizes for raising. the temperature of oil or gas to elevated temperatures such as are useful and necessary for cracking, reforming and various other analogous operations.

In our United States Patent 2,294,254, issued August 25, 1942, we have shown and described a heater of this general type in which the walls of the" furnace chamber slope inwardly from the bottom to the top, but in this case the slope is slight and the heat exchange tubes within the chamber are arranged substantially in the same fashion as if the chamber walls were cylindrical.

The heater of this invention has a number of distinct advantages over previous structures, and certain of the objectives are as follows:

(l) The tall upright furnace'chamber has a distinct inward slope from bottom to' top, and continues beyond the convection section of the heater to form a portion of the stack. In this way the heater has a very broad base relative to the top and the frusto-conical shape of the" chamber and thecha'mber walls themselves are entirely adequateto supp'ort thes'ta'ck portion and the usual tall stack without requiring any structural steel support? ing elements such as} are usually mounted on the outside of the chamber walls; Thisresu'lts in a'very substantialsaving' in theinvestmerit' costand' increases the stability of the heateri p (2) The heat eXchangec'oils are spaced inwardly from the chamber wall, and at the bottom they are spaced from each other in the form of a single circle. At the top, on the other hand, the chamber is narrowed down to such an extent that a special arrangementof the tubes is made'as' hereinafter described.

(3) A frusto-conical baffle of somewhat smaller diametric'al dimensions is hungin theupper end of the heater with its smaller end upward and its largeie'nd downward to c'onfo rin'to the contour of the upper endo'f'the furnace chamber. This baflle is closed at the top and is open at the bottom so as 'to savernetal.

(4) Certain'spaced tubes extendall the way to the top of the heater and others' extend onlyclose to the bottom of the bafile, and in' this fashion the proper spacingof the tubes is maintained'inspite' of the wide'differe'nce in diameter between the botteni and top'o'f the heater;

Referiingto the drawings: A L

'Figurel is apartially sectional elevation withce rtin of the heating tubesornitted'fofclarityg a V Fig. 2 is a'sectional plan View 031 the line 2--2 ofFig 1 which shows the arrangement of the heat exchange tubes at the bottom of the heater; r

Fig. 3 is'a sectional plan view on theline 3*3' of Fig. l which shows'the tube arrangementnear the top of the furnace chamber but just below the baffie;

Fig. 4 is a partially sectionalpla'n view on the line 44 of Fig. 1 which showsthe'tube arrangement-in the convection section formed between thebafileaand the ad jacent wall of thefurnace chamber;

Fig; 51 is a View corresponding? to 1 thatofFig-i of the 2,955,080 Patented Dec. 20, 1960 'ice 2 heater which constitutesv another embodiment' of this invehti on; I I

Fig. dis a' sectional plan-view 'take'non the line 6-6 of Fig. 5; and I Fig. 7 is a partially sectional plan view taken on the line 7-7 of Fig. 5.

Fig. 8 is a detailed sectional view taken on the line 88 of Fig. 5.

Referring specifically to Figs. 1 to 4, the heater illus trated comprises a-frusto-conical combustion chamber 10 which is built of relatively heavy steel plate and has a refractory lining. 11 on its inner surface. A substantially horizontal bottom plate l2 is welded or otherwise secured to the chamber walls at the bottom-and hasone or more upshot burners 13,. four being illustrated as shown: in Fig.2, mounted in the'bottorn plate so as to provide a column of flame andhot gases which rises upward alongthe'central axis of the heater.

The chamberissupported from foundation 14 bya plurality of structural steel legs 15 which are welded to the chamber Wall near the bottom and extend to the foundation. Legsextend as a'continuation of the contour of the furnace chamber so that they are widely spread apart at the foundation and support the bottom plate of the furnace chamber at suificient height to enable attendants to stand erect below the bottom of the heater for the purpose of adjusting the burners or performing any other necessary functions. 7

A plurality of heat exchange tubes 16,17 and 18 are spaced inwardly from the furnace chamber walls and are equally spaced from each other in-a circular bank at the bottorno'fthe heateras shown in Fig; 2. I The tubes 1 6 and 18 and 17 a'nd 18 are interconnected at the bottorn by return bends which are supported in grooves in the bottom plate 12 in the same manner tubes 54 and 51', as'shown inFig. 8. H p

Tubes 18, which inthe structureillustrated are arranged inpairs that are separated from each other by one tubefld aiid one tube 17, extend parallel to the chamber' wallall the way to the top of the chamber and are interconnected by return bends 19 as shown in Fig.- 4. The taper of the furnace chamber is such that the tubes 18are -equally spaced from each other in a circular bank at the top as shown in Fig. 4. i

In order to accommodate the tubes 1-6 and 17, which cannot be extended all the way to the top of the heater because of lack of space, they are interconnected by return bends 20 just below the convection section of theheaterwhich is, hereinafter described;

At this point, as shown'in Fig. 3, there is room for the tubes 16 and 18' to be spaced in a circularbank,.wh e reasthe tubes 17 are sloped from the single circle of Fig. 2- atthebottom to an inner circle at the return bends'as shown in Fig. 3. v

A convection section of the furnace is'formed attheupper end by a frusto-conical bafile 25 which follows the contour of the furnace chamber walls but is diametrically smaller in dimensions so as to leave an-- annular;

frusto-conical space 26,. through which the upper ends of the tubes l S-extend In this section of the heater-the: tubes 18, have extended surface elements as shown-at 1ugs30 on the'outer surface of the stack portion3l which' is a' continuation of the frusto conical furnacechamber and constitutes asupportfor the stack 32. 1

In operation of the burners 13 discharge axially upward hot flame and combustion products which soon fill the inside of-the'ba'fileZS and then ovenl'low and pass at -1inusually? h g cib"- thr gh the annular spaee Marthe convection section and are thence discharged through stack portion 31 into stack 32.

The tubes 16, 17 and 18 are all heated primarily by radiation from the bottomof the heater to the bottom of the bafiie, radiated heat being supplied directly from the flame and not gases in the center and by reradiation from the refractory lining 11 which is heated by direct radiation from the flame and hot gases to a very high temperature and reflects its heat.

The tub-es are interconnected in any suitable manner but preferably so that there is a single inlet 35 and an outlet 36 located in the bottom of the furnace below the bottom plate 12.

Referring now to Figs. 5, 6 and 7 of the drawings, the structure here shown is similar in many respects to that of Figs. 1 to 4, inclusive, and the same reference characters indicate the same parts. In this structure the baffle 37 is smaller in its dimensions but similar in its shape to that of baflie 25 so that a wider annular space 38 is provided and is adequate to receive a double row of fin tubes arranged in circles 39 and 40 as shown in Fig. 7 and interconnected at the top by return bends 41.

The tubes in circle 40 are spaced closer together than the tubes in circle 39 so that the same number of tubes is accommodated in each circle and the return bends 41 are inclined so that the tubes of the circle 40 are not directly in the same radius as the corresponding tubes in circle 39, the arrangement being such that the fin tubes closely fill the annular space 38 which constitutes the convection section of the heater.

Tubes which are designated 50 and 51 are equally spaced in a circular bank at the bottom of the heater as shown in Pig. 6, and tubes 50 slope inwardly so that their upper ends are in the inner bank 40, whereas the tubes 51 extend all the way parallel to the inner wall of the furnace chamber and terminate in tube circle 39. At the bottom the tubes 50 and 51 are interconnected by return bends 50a supported in grooves 51a in the bottom plate 12. In this way the weight of the tubes is carried by the bottom plate.

' In the operation, burners 13 discharge flame and hot combustion gases upward in an axial direction, which gases fill the baffle 37, overflow and flow around and among the fin tube sections 60 of the tubes 50 and 51 at high speed.

The tubes are heated by radiation from the central flame and hot gases and by reradiation from the refractory lining 11 of the furnace chamber 10.

The structure illustrated is relatively low in cost because of the absence of the usual structural steel sup ports which normally extend the entire length of the heater and carry the stack at the top. The wide spread of the heater at the bottom gives it unusual stability.

In the section of the heater below the baffle where the tubes are interconnected at the top by radially extending return bends in the structure of Fig. 1 and approach radial spacing in the arrangement of Fig. 5, the tubes are supplied with heat both by radiation and by convection, whereas lower down in the furnace chamber the tubes are heated almost entirely by radiation.

The furnace of this invention with a large base and a very small opening at the top has the distinct advantage of producing an unusually high gas velocity through the convection section, with a consequent increased rate of heat transfer.

The drawings and the specific embodiments described are intended to be illustrative only and constitute what we now regard as the best embodiment of our invention. Other modifications may be made without departing from the spirit of the invention, and only such limitations should be imposed as are indicated in the appended claims.

What we claim is: Y

1. An upright heater comprising a frusto-conical conr bustion chamber having a large circular bottom plate, at

least one burner mounted therein and discharging flame and combustion gases upwardly in a substantially vertical path within the chamber, a plurality of heat exchange tubes spaced from each other and from the inner wall of the frusto-conical combustion chamber and having their bottom ends arrangedin a single circular row, a frusto-conical baflie depending from the top of the combustion chamber and corresponding in shape to the upper end of said chamber but of smaller diametrical dimensions to provide a frusto-conical annular convection chamber, a uniformly distributed number of said heat exchange tubes being elongated to extend through the convection chamber and having extended surface elements in said convection chamber, return bends interconnecting the elongated tubes at their top ends, radially extending return bends interconnecting the remainder of said heat exchange tubes in pairs at the top of the combustion chamber below the convection chamber and circumferentially extending return bends interconnecting the bottom ends of the tubes in the circular row at the bottom of the heater.

\ 2. An upright heater comprising a frusto-conical combustion chamber having a large circular bottom plate, at least one burner mounted therein and discharging flame and combustion gases axially upward within the chamber, an upright heating coil within the chamber having a plurality of long heat exchange tubes spaced from one another and from the walls of the combustion chamber, the bottom ends of the tubes being arranged in a single large circular row, circumferentially extending return bends interconnecting the bottom ends of the tubes in pairs in said large circular row, certain uniformly distributed ones of said tubes being inclined inwardly whereby the top ends of the tubes form two small concentric wall, legs attached to the furnace cone at the bottom extending downwardly and outwardly to form a continuation of the furnace wall and holding the cone at a spaced position above the foundation, a horizontal bottom plate closing the furnace shell at the bottom of the cone, one or more upshot burners mounted in the bottom plate and adapted to discharge flame and combustion products axially upward within the conical furnace chamber, a plurality of straight heat exchange tubes within the cone and spaced from its wall, said tubes being equally spaced from each other and their lower ends being arranged in a single circular row at the bottom of the furnace and interconnected in pairs by circumferentially extending return bends mounted in grooves in the bottom plate and interconnected in pairs by radially extending return bends at their top ends to form two concentric circular rows of tube ends near the top of the furnace.

4-. A streamlined upright heater comprising a tall frusto-conical furnace chamber with a broad base and the small end of the cone upward, a frusto-conical stack portion mounted onthe top of the furnace with its larger end sized to correspond to the small end of the frustoconical furnace chamber and its side walls constituting a continuation of the frusto-conical furnace chamber wall, legs attached to the frusto-conical furnace chamber at the bottom extending downwardly and outwardly to form a continuation of the frusto-conical furnace chamber wall and holding the said furnace chamber at a spaced position above the foundation, a horizontal bottom plate closing the furnace shell at the bottom of the cone, one or more .upshot burners mounted centrally in the bottom plate and adapted to discharge flame and combustion products axially upward within the frusto-conical furnace chamber, a plurality of straight heat exchange tubes within the frusto-conical furnace chamber and spaced from its wall, the bottom ends of said tubes being equally spaced from each other in a single circular row at the bottom of said furnace chamber and interconnected at their upper ends to form two concentric circular rows near the top of the furnace chamber and extended 'surface means on the tubes near the upper end of the furnace chamber adapted to form a convection section of the heater.

5. A streamlined upright heater comprising a tall frusto-conical furnace chamber with a broad base and the small end of the cone upward, a frusto-conical stack portion mounted on the top of the furnace with its larger end sized to correspond to the small end of the furnace cone and its side walls constituting a continuation of the furnace wall, legs attached to the furnace cone at the bottom extending downwardly and outwardly to form a continuation of the furnace wall and holding the furnace chamber at a spaced position above the foundation, 2. horizontal bottom plate closing the furnace shell at the bottom of the cone, one or more upshot burners mounted in the bottom plate and adapted to discharge flame and combustion products axially upward within the frustoconical furnace chamber, a plurality of long, straight heat exchange tubes within the cone and spaced from its wall, the bottom ends of said tubes being equally spaced from each other in a single circular row and interconnected in pairs at thebottom of the furnace and said tubes being spaced in two concentric circular rows and interconnected in pairs at their upper ends, a frusto-conical baffle shaped to correspond to, but of smaller dimensions than, the upper end portions of the furnace to form a narrow annular convection section, said baffle having its upper smaller end closed by a top plate and its lower end open, and extended surface means on the tubes at the upper end of the furnace where they extend into the convection section.

References Cited in the file of this patent UNITED STATES PATENTS 2,294,254 Throckmorton etal Aug. 25, 1942 2,333,077 Wallis et a1 Oct. 26, 1943 2,479,544 Schauble Aug. 16, 1949 2,544,600 Keller Mar. 6, 1951 2,617,405 Keller Nov. 11, 1952 

